Conventional reinforcements for casting comprise reinforcement rods which are attached to each other in structures. Such reinforcements have the disadvantage of providing a relatively poor load resistance to weight ratio. Furthermore, handling of the reinforcement rods and assembling them into reinforcement structures is a time consuming and heavy task.
Reinforcements with ring-shaped reinforcement elements are known and have the advantage that the ring-shaped structure provides a high load resistance. Ring-shaped structures are also advantageous because of their uni-directional load resistance properties. Ring-shaped reinforcement elements can not be locked to each other in an easy and natural way, as for example crossed straight reinforcement rods.
It is known to use small ring-shaped reinforcement elements which are mixed into the material in which they are to be casted. One example of such reinforcement elements is disclosed in U.S. Pat. No. 3,616,589A, which describes a reinforcement with ring-shaped reinforcement elements which are randomly distributed in the material in which they are casted into. WO0155046A2 also describe reinforcement elements of this type. The reinforcement elements comprise a longitudinally extending body having ring-shaped elements coupled to each end thereof. Such reinforcement elements have the disadvantage that the longitudinally extending body has a much lower load resistance than the ring-shaped elements, thereby providing a highly non-uniform load resistance of the reinforcement elements. In general, it is difficult to distribute the reinforcement elements evenly and they are not interconnected. Another disadvantage of this type of reinforcement elements is that the reinforcement in it self due to their small size adds little structural strength to the object into which they are casted (unlike for example a conventional reinforcement rod). Therefore, they are not suitable for applications where a high tensile strength is required.
Another type of reinforcement is also known, where individual ring-shaped reinforcement elements are linked together in various patterns. JP1153563A discloses a reinforcement with ring-shaped reinforcement elements which have been linked together in chains. The linking together requires individual handling of each ring-shaped reinforcement element, which is time and cost demanding. U.S. Pat. No. 1,610,996A discloses a reinforcement with ring-shaped reinforcement elements which have been linked together to with a byrnie, which also requires individual handling of each ring-shaped reinforcement element. Such linked together reinforcements may also provide a non-uniform strength and a low overall strength of the reinforcement it self.